Current transformers are commonly used in metering and protective relaying in power industry where they facilitate safe measurement of large currents, often in the presence of high voltages. The rapid growth and high demand in the power generation, transmission and distribution systems impels all manufacturing utilities to design compact, optimal and cost-efficient power equipment like current transformers.
Generally, a current transformer of top core design is formed by a top head housing supported by a hollow tubular insulated column, which is, in an embodiment, fixed on a grounded base. Secondary windings are enclosed in a metallic core casing, which in turn is connected to the ground through metal tube passing centrally through the hollow insulator. Either the metallic core housing or primary conductor is insulated for the voltage class.
The top head housing generally consists of two parts fixed together, a lower part and an upper part.
Generally, the lower part is bigger and comprises most of the means for supporting the other parts of the current transformer. The upper part, of smaller size, is mostly used to hermetically close the head housing.
The two parts of the top head housing are generally made by molding. Then, the manufacturing of the top head housing needs two sets of molds.
Embodiments of the invention aim to reduce the costs and to simplify the production of the parts of a top head housing.